1. Field of the Invention
The invention relates to a vehicle tire safety device, and more particularly, to an airbag device for a vehicle tire, which allows the tire to continue operating safely after failure, e.g., explosion or puncture, without loss of stability and for an extended period of time without the need for tire replacement.
2. Description of the Related Art
Conventional vehicle tires are air-filled (pneumatic) and offer the advantages of good comfort and low road resistance. However, air-filled tires are prone to failure and loss of pressure at which time flat tires must be replaced immediately. Especially, when a tire has exploded or is punctured suddenly at a high running speed, the vehicle may lose balance potentially causing a serious accident. Many solutions to this problem have been proposed.
The solutions are mainly classified into two types. The first type is to install a supporting rim inside of the tire. See, e.g., Chinese Pat. Publ. No. CN1616264A. While the tire structure is not changed, the outer diameter of the supporting rim is less than the inner diameter of the tire tread and is more than the outer diameter of the wheel hub. If the air pressure of the tire is lost, the weight of the auto will be supported by the supporting rim so that the falling height of the wheel is decreased to realize a certain degree of safety protection. However, since the outer diameter of the supporting rim is less than the inner diameter of the tire tread, the tire rolling resistance is increased.
The other type is to improve the tire structure to allow the tire to have certain supporting strength after puncture to allow the tire to run a further distance. The existing fail safe tires are described, e.g. in China Pat. CN1264343A, China Pat. CN1265067A, and China Pat. CN1689847A. The fail safe tire has a similar shape and shares the same installation method as a normal pneumatic tire. However, since enough supporting strength needs to be ensured, the riding comfort is decreased and the resistance of the wheel is increased during normal operation.